Carbon and Carbon Hybrid Materials as Anodes for Sodium-Ion Batteries

Synergistic interface and structural engineering for high initial coulombic efficiency and stable sodium storage in metal sulfides

Transition metal sulfides (TMS) have gained significant attention as potential anode materials for sodium ion batteries (SIBs) due to their high theoretical capacity and abundance in nature. Nevertheless, their practical use has been impeded by challenges such as large volume changes, unstable solid electrolyte interphase (SEI), and low initial coulombic efficiency (ICE). To address these issues and achieve both long-term cycling stability and high ICE simultaneously, we present a novel approach involving surface engineering, termed as the "dual-polar confinement" strategy, combined with interface engineering to enhance the electrochemical performance of TMS. In this approach, CoS crystals are meticulously coated with polar TiO2 and embedded within a polar S-doped carbon matrix, forming a composite electrode denoted as CoS/TiO2-SC. Significantly, an ether-based electrolyte with chemical stability and optimized solvation properties synergistically interacts with the Co-S-C bonds to create a stable, ultra-thin SEI. This concerted effect results in a notably high ICE, reaching approximately 96%. Advanced characterization and theoretical simulations confirm that the uniform surface modification effectively facilitates sodium ion transport kinetics, restrains electrode pulverization, and concurrently enhances interaction with the ether-based electrolyte to establish a robust SEI. Consequently, the CoS/TiO2-SC electrode exhibits high reversible capacity, superior rate capability, and outstanding cycling stability.

MoS2/SnS/CoS Heterostructures on Graphene: Lattice-Confinement Synthesis and Boosted Sodium Storage

The development of high-efficiency multi-component composite anode nanomaterials for sodium-ion batteries (SIBs) is critical for advancing the further practical application. Numerous multi-component nanomaterials are constructed typically via confinement strategies of surface templating or three-dimensional encapsulation. Herein, a composite of heterostructural multiple sulfides (MoS2/SnS/CoS) well-dispersed on graphene is prepared as an anode nanomaterial for SIBs, via a distinctive lattice confinement effect of a ternary CoMoSn-layered double-hydroxide (CoMoSn-LDH) precursor. Electrochemical testing demonstrates that the composite delivers a high-reversible capacity (627.6 mA h g-1 after 100 cycles at 0.1 A g-1) and high rate capacity of 304.9 mA h g-1 after 1000 cycles at 5.0 A g-1, outperforming those of the counterparts of single-, bi- and mixed sulfides. Furthermore, the enhancement is elucidated experimentally by the dominant capacitive contribution and low charge-transfer resistance. The precursor-based lattice confinement strategy could be effective for constructing uniform composites as anode nanomaterials for electrochemical energy storage.

Small-Molecule Organic Cathodes with Carbon Coating for Highly Efficient Potassium-ion Batteries

Small-molecule organic cathodes face dissolution in potassium-ion batteries (PIBs). For the first time, an interesting and effective strategy is unveiled to resolve this issue by designing a new soluble small-molecule organic compound namely [N,N'-bis(2-anthraquinone)]-1,4,5,8-naphthalenetetracarboxdiimide (NTCDI-DAQ, 237 mAh g-1 ): Through the precise manipulation of carbonization temperature and time, the molecules on the surface of NTCDI-DAQ particles can be transformed into amorphous carbon with controllable thickness. This strategy called surface self-carbonization can form a carbon protective layer on organic cathodes and significantly increase their insolubility against liquid electrolytes without affecting the electrochemical behavior of bulk particles. As a result, the as-obtained NTCDI-DAQ@C sample displays significantly improved cathode performance in PIBs. In half cells, NTCDI-DAQ@C shows superior capacity stability of 84 % compared to 35 % of NTCDI-DAQ during 30 cycles under the same conditions. In full cells with a KC8 anode, NTCDI-DAQ@C delivers a peak discharge capacity of 236 mAh g-1 cathode and a high energy density of 255 Wh kg-1 cathode in 0.1-2.8 V, with 40 % capacity retention during 3000 cycles at 1 A g-1 . To the best of our knowledge, the integrated performance of NTCDI-DAQ@C is among the best of soluble organic cathodes reported in PIBs.

Understanding the Highly Reversible Potassium Storage of Hollow Ternary (Bi-Sb)2S3@N-C Nanocube

Metal sulfide anodes have aroused much attention in potassium ion batteries (PIBs) owing to their high theoretical capacities, but the sluggish kinetics and inferior cycling performance caused by severe volumetric change and particle pulverization greatly hinder their further development. Herein, robust hollow structure design together with phase structure engineering endow (Bi-Sb)₂S₃@N-C anode with superior (de)potassiation kinetics and excellent electrochemical performances in PIBs. Specifically, in situ X-ray diffraction combined with density functional theory calculations and ex situ X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy (TEM) analyses indicated a fresh reaction mechanism of (Bi-Sb)₂S₃ anode with a distinctive multistep (de)potassiation route along (003) plane of (Bi,Sb) alloy thanks to the Bi-Sb phase regulation in (Bi-Sb)₂S₃ anode, ensuring it with superior reaction kinetics. Moreover, in situ TEM characterization revealed the advantages of the hollow nanostructure with carbon shell, facilitating fast ion transport kinetics and high tolerance of volume change as well as enabling the structural integrity of electrode material during (de)potassiation. As a result, the (Bi-Sb)₂S₃ hollow nanocube with N-doped carbon shell ((Bi-Sb)₂S₃@N-C) delivers a high initial Coulombic efficiency of 66.3%, a great rate performance of 289 mAh g^-1 at 2.0 A g^-1, and an ultralong cycling life (89% retention after 220 cycles at 0.1 A g^-1 and 85% retention after 1600 cycles at 2.0 A g^-1) in PIBs. Furthermore, the full cell of (Bi-Sb)₂S₃@N-C//PTCDA affords a high reversible capacity of 281 mA h g^-1 at 1.0 A g^-1 after 300 cycles. This work combines structural design and in situ techniques, proving a successful nanostructure engineering strategy to rationalize alloy-type electrode materials for PIBs.

Facile synthesis of SnNb2O6@C composite with ultrathin carbon layer as anode materials for high-performance sodium-ion batteries

Niobium-based oxides have attracted a lot of attention as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, excellent rate capability and exceptional safety. However, their poor intrinsic electronic conductivity and sluggish sodium ions diffusion kinetics severely hinder their practical applicability. Here, SnNb 2 O 6 @C was successfully prepared by a simple solid-state reaction technique coupled with carbon coating. HRTEM images show that the SnNb 2 O 6 @C particles are covered by a uniformly ultrathin amorphous carbon layer of about 1.8 nm, thus improving the electronic conductivity and diffusion coefficient of sodium ions. As anode for SIBs, the as-obtained SnNb 2 O 6 @C material exhibits excellent specific capacity (369 mAh g -1 at a current density of 50 mA g -1 ) and remarkable rate performance (177 mAh g -1 at 1000 mA g -1 ), which indicates its good prospect in practical application.

Investigation of pyrolysed anthracite as an anode material for sodium ion batteries

Due to the increasingly serious problems of the greenhouse effect and environmental pollution caused by the continuous consumption of traditional fossil energy, renewable and clean energy (such as solar energy and wind energy) is facing new opportunities and challenges.

Single-Step Synthesis of Mesoporous Carbon Nitride/Molybdenum Sulfide Nanohybrids for High-Performance Sodium-Ion Batteries

Molybdenum disulfide (MoS₂ ) is a promising candidate as a high-performing anode material for sodium-ion batteries (SIBs) due to its large interlayer spacing. However, it suffers from continued capacity fading. This problem could be overcome by hybridizing MoS₂ with nanostructured carbon-based materials, but it is quite challenging. Herein, we demonstrate a single-step strategy for the preparation of MoS₂ coupled with ordered mesoporous carbon nitride using a nanotemplating approach which involves the pyrolysis of phosphomolybdic acid hydrate (PMA), dithiooxamide (DTO) and 5-amino-1H-tetrazole (5-ATTZ) together in the porous channels of 3D mesoporous silica template. The sulfidation to MoS₂ , polymerization to carbon nitride (CN) and their hybridization occur simultaneously within a mesoporous silica template during a calcination process. The CN/MoS₂ hybrid prepared by this unique approach is highly pure and exhibits good crystallinity as well as delivers excellent performance for SIBs with specific capacities of 605 and 431 mAhg^-1 at current densities of 100 and 1000 mAg^-1 , respectively, for SIBs.

Ultrafine Co1-xS Attached to Porous Interconnected Carbon Skeleton for Sodium-Ion Batteries

Carbon-based materials are effective carriers of metal sulfides because of their good volume stability and chemical stability, which can reduce volume expansion of materials and can also inhibit the interfacial reaction. In this study, Co_1-xS incorporated into three-dimensional porous biomass carbon skeleton were synthesized by a template method. The three-dimensional porous carbon with large surface area is favorable for the electrolyte infiltration. The uniform distribution of Co_1-xS nanoparticles results in a high reversible electrochemical reaction. The well-designed Co_1-xS/three-dimensional porous carbon structure exhibits outstanding performance when used as an anode for sodium-ion batteries (SIBs). The results show that the transition mental sulfide/three-dimensional porous carbon structure has broad application prospects in SIBs.

Hierarchical Interconnected Expanded Graphitic Ribbons Embedded with Amorphous Carbon: An Advanced Carbon Nanostructure for Superior Lithium and Sodium Storage

Carbon materials have attracted considerable attention as anodes for lithium-ion and sodium-ion batteries due to their low cost and environmental friendliness. This work reports an advanced carbon nanostructure that takes advantage of the chelation effect of glucose and metal ions, which ensures the uniform dispersion of metal in the precursor. Thus, an effective catalytic conversion from sp³ to sp² carbon occurs, enabling simultaneously formation of pores with catalyzed graphitic structures. Due to the low carbonization temperature and short carbonization time as well as the different catalytic degree of various metals, a series of expanded graphitic layers from 0.34 to 0.44 nm with defects and amorphous carbon structure are obtained. The structure not only offers accessible graphitic spacings for reversible lithium/sodium ion insertion, but also provides abundant active sites for lithium/sodium ion adsorption in the defects and amorphous structure. Moreover, the hierarchical interconnected porous structure combining graphitic ribbons is beneficial for fast electronic/ionic transport and favorable electrolyte permeation. More importantly, such advanced carbon materials prove their feasibility for balancing the pore structure and degree of graphitization. When serving as the electrode material for lithium-ion and sodium-ion batteries, excellent electrochemical performance along with fast kinetics and long cycle life is achieved.